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Easter Island drug improves learning and memory in mice of all ages

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July 1, 2012

Rapamycin, a bacterial product first discovered in a soil sample from Easter Island, has b...

Rapamycin, a bacterial product first discovered in a soil sample from Easter Island, has been found to enhance learning and memory in young and old mice alike (Image: Shutterstock)

Rapamycin, a bacterial product first discovered in a soil sample from Easter Island – also known as Rapa Nui, hence the name – is an immunosuppressant drug used to prevent rejection in organ transplants that has now been found to enhance learning and memory in young and old mice alike. Researchers at the School of Medicine at The University of Texas (UT) Health Science Center San Antonio made the discovery while looking for a way to prevent the decline in cognitive skills that comes with age.

The researchers added rapamycin, which is also known as sirolimus and is marketed by Pfizer under the trade name Rapamune, to the diet of healthy mice throughout their lifespan and found the drug's effects held true for mice of all ages.

“We made the young ones learn, and remember what they learned, better than what is normal,” said Veronica Galvan, Ph.D., assistant professor of physiology at the Barshop Institute for Longevity and Aging Studies, part of the UT Health Science Center. “Among the older mice, the ones fed with a diet including rapamycin actually showed an improvement, negating the normal decline that you see in these functions with age.”

Dr. Galvan said the drug also lowered anxiety and depressive-like behavior in mice – both factors that impair human cognitive performance.

As burrowers that prefer tunnels with walls, mice are uncomfortable in open spaces. So, to observe the behavior of the mice, the researchers used an elevated maze that led to an open catwalk. Compared to those with a regular diet, they observed that mice fed with a diet containing rapamycin spent significantly more time exploring the catwalk, indicating they experienced less anxiety.

A second test to measure the depressive-like behavior of the rodents took advantage of the fact that mice don’t like to be held by their tails. As this is the way they are moved from cage to cage, they inevitably struggle to find a way out, and how much and how often they struggle can provide a measure of the motivation to get out of an uncomfortable situation.

Some mice barely struggle to get free, but if an antidepressant is administered they struggle a lot more. This behavior is very sensitive to the action of antidepressants and is a reliable measure of whether a drug is acting like an antidepressant, Dr. Galvan said.

“We found rapamycin acts like an antidepressant – it increases the time the mice are trying to get out of the situation,” she said. “They don’t give up; they struggle more.”

The team says the reduction in anxiety and depressive-like behavior in the mice treated with rapamycin was observed in all ages tested, from four months of age, which equates to college age in human years, to 12 months old, which is equivalent to middle age, right through to 25 months of age, which equates to advanced age in humans.

The researchers also measured levels of serotonin, dopamine and norepinephrine, which are “happy, feel-good” neurotransmitters. All three of these chemical messengers in the brain were significantly elevated in the mice treated with rapamycin, which Dr. Galvan says may explain rapamycin’s effects.

The team’s study was published last week in the journal Neuroscience.

Source: UT Health Science Center

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
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6 Comments

The Rats of NIMH are coming : )

Tricia Thompson-Browne
2nd July, 2012 @ 04:06 am PDT

University of Texas? Isn't that a government agency doing great research work for medical science? Isn't this a great discovery, help for the aged and transplant patients? Now if we could only keep it from falling into the hands of 'for profit' health companies who imagine that they did all the work and can charge the Commons without paying us royalties. The US government should be the ones patenting these inovations in the name of its citizens. If industry wants to use them let them lease from us and accept government regulation of use and costs.

Jansen Estrup
2nd July, 2012 @ 09:13 am PDT

Intriguing and problematic at the same time. The implication is that it might have similar cognitive and affective benefits in humans - except the drug is primarily known for its immunosuppressant properties. Get smart, maintain a happy mood, and die of a variety of diseases from which our immune system normally protects us.

What would Charlie say?

Loving It All
2nd July, 2012 @ 09:32 am PDT

Did you know Pfizer's offers of this "wonder, make happy make smarter" drug under the trade name Rapamune and they charge people something like US$900 a month for it?

Hmmm. Makes you think that Pfizer's PR department might be taking it themselves and came up with the idea of channeling funds to researchers to find a wider market than organ transplant victims - thus making their share holders happy.

My wife points out that if this came from soil bacteria on Rapa Nui then it must not have done the residents of that island much good. Aside from creating hallucinogenic stone statures with big red hats they destroyed the ecology of their own island and most of them perished.

Richard Chesher
2nd July, 2012 @ 01:48 pm PDT

Yes, maybe, but I hear the rats the settlers brought with them were in good part the devourers of the palm forest. The rats ate much of the seed and the settlers did the rest. This theory also says the island was deforested quickly after the arrival of the first Polynesians around 1200 CE. The 3000 islanders found in 1722 were 'rubbed out' by western disease and colonialist contempt. So, maybe this is another of those infestation-followed-by-colonial-encounter extinctions and not simply a cut and burn case of overpopulation and anxious self-destruction.

Manfred
2nd July, 2012 @ 08:53 pm PDT

I'm going to Rapa Nui and gonna eat me some dirt LOL. Cut out the middle man and get a fun vacation out of it.

Fabian Rousset
6th July, 2012 @ 05:58 am PDT
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